Data Protector: Exchange backup failes because of database lock

Today I had a customer call, where a Exchange 2010 backup repeatedly failed. HPE Data Protector was unable to create a differential or incremental backup. For each database, the following error was logged:

[Minor] From: OB2BAR_E2010_BAR@exchangeserver.domain.tld "MS Exchange 2010+ Server"  Time: 21.03.2016 20:00:27
[170:313] 	One or more copies of database DATABASE are already being backed up in a different session.

Interestingly, there was no other backup session running. But the night before, the backup jobs failed because of a network failure.

The solution is easy. This error is caused by a wrong information in the Data Protector database. To remove this, open an administrative CMD on the Data Protector Cell Manager and run this omnidbutil command:

C:\Users\Administrator>omnidbutil -free_cell_resources
DONE!

This command  will free up the locked resources in the Data Protector database.Then, run the job again.